The 22-year-old representative centre didn't confirm he'd be joining the Rabbitohs on what is understood to be a cut-price one-year deal but did announce his time with the Roosters is over.

"I can not describe the way I feel right now but just wanted to let everyone know involved in my career through my stint here, I am so very grateful for you all," Mitchell posted on his Instragram account on Friday.

"Nothing has been made official as of yet. But my stay at the roosters has come to an end.

"On to the next chapter where ever that may be."

That next chapter is expected to be at Redfern, with multiple sources reporting Mitchell will be linking up with his new teammates at pre-season training on Monday.

It's unclear if the deal Mitchell has reportedly signed with Souths is the original one-year $400,000 offer that was first tabled or if Gold Coast's reluctance to allow forward Jai Arrow to join Souths in 2020 has allowed the Rabbitohs to increase their offer.

Mitchell's future has been up in air for several weeks despite the 22-year-old being under contract with the Sydney Roosters for 2020.

The NRL premiers granted Mitchell leave before the start of their pre-season training and withdrew an $800,000 per season contract offer.

Wests Tigers also reportedly offered Mitchell $1 million per season but couldn't finalise a move.

It's understood NRL salary cap auditor Richard Gardham needs to ratify the move before any official announcement can be made.

The Roosters are also expected to ask for the $116,000 they have paid Mitchell since November to be returned to them, the Sydney Morning Herald reports, in another stumbling block to the move.

Gardham has announced he'll use the earnings of every player in the competition to determine Mitchell's market value.

Australian Associated Press